The front-end is called Piper, so I would install that, and it comes with the required library and the daemon. Piper is OK, but the CLI is sometimes better. The UI doesn't default to your active profile, and I always have to change it to do anything, even though it's my only profile.

The only thing ratbagd couldn't do is set a button to be a pure modifier key like Ctrl or Shift. I had to boot up Windows to do that. The macro that the Logitech software creates in order to have the mouse send a pure modifier key is weird. It's a three step macro instead of just the key, and ratbagd doesn't even display it correctly. It might be fixed in the future. Who knows.